Usually a polite and elegant beauty with long black hair, her defining trait is the contrast between her normal self and the madness she displays during a gamble. The Ultimate Gambling Freak: She finds pure joy in taking risks and feels an intense pleasure in high-stakes, life-or-death matches. Fearless: Even in situations where losing means forfeiting her entire fortune or her life, she dives into high-stakes bets without hesitation. The more insane the match, the happier she is, preferring situations where massive sums or lives are on the line.

A person with a free-spirited yet cold-blooded and insane side, possessing overwhelming talent for gambling. President of the Hyakkaou Private Academy Student Council: The absolute ruler of the school, she created the unique hierarchy and house pet system. Overwhelming Charisma: Feared yet worshipped by the students, she is truly the master of the "aquarium." The 105th Student Council President: She won her seat in her first year by defeating the previous president in a gamble.

A spirited and beautiful girl characterized by her blonde twin-tails. She possesses high intelligence, a calculating mind, and an extreme hatred of losing. Calculating Intellectual: Contrary to her cute appearance, she is very quick-witted and excels at seeing through the core of games and spotting cheats. Extreme Sore Loser: She possesses an obsession with winning that makes her willing to use dirty tactics if necessary. Strong-willed and Haughty: Initially confident and prone to looking down on others, she grows significantly throughout the story.

A mysterious figure who overwhelms those around her with rough speech and eccentric behavior, while also possessing cold-blooded observational skills. Characterized by an eyepatch, numerous piercings, and sanpaku eyes, she loves gambling that puts her own life at risk and has intense emotional swings. Intense Masochistic Gambler: She has a very strong tendency to find pleasure in death, defeat, and physical or mental pain, valuing thrills above all else. Mad and Violent: She always speaks in a rough tone and behaves aggressively, such as carrying a handgun. She stands out as particularly eccentric even among the many weirdos in the cast.

Despite her young appearance at 130cm tall, always wearing a rabbit kigurumi hoodie and acting playfully while eating candy, she is cold-hearted and maintains absolute neutrality—an elusive and mysterious character. Cold-hearted Nature: Contrary to her bright and flippant behavior, she is very cold inside and has a cruel personality that finds amusement in the misfortunes and predicaments of others.

Though timid and cowardly, he has a strong sense of compassion for others and is the "conscience" of the series, always staying by Yumeko's side as her close confidant.

The calm, collected, and rational Student Council Secretary.